1. Field
Apparatuses and methods consistent with the present disclosure relate to audio signal processing and, more particularly, to audio signal processing of sigma-delta modulation of an input audio signal.
2. Description of the Related Art
Class A, B, C, and Class D amplifiers are used to receive audio signals and output audibly perceptible signals. A Class D amplifier reduces deterioration in amplification efficiency that occur in class A, B, and C amplifiers. The Class D amplifier exhibits higher amplification efficiency than class A, B, and C amplifiers. Thus the Class D amplifier is widely used.
A Class D amplifier is a digital amplifier that modulates analogously input audio signals to produce digital audio signals, and amplifies and output digitally modulated audio signals.
Digital amplifiers have no data conversion loss and achieve amplification efficiency of 100% theoretically and thus are widely used.
Digital amplifiers modulate input audio signals to produce pulse signals and amplify the pulse signals. Sigma-delta modulation may be used to modulate audio signals to produce pulse signals. A modulator using sigma-delta modulation is referred to as a sigma-delta modulator.
A high order sigma-delta modulator may be used to enhance noise shaping.
However, a high order sigma-delta modulator accumulates signal values, which causes a large amount of oscillation to occur as the order of the sigma-delta modulator increases. The occurrence of oscillation may hinder the ability of the sigma-delta modulators to perform modulation operations, and thus an operation stability of sigma-delta modulator may not be secured.